Micrometer.



W. F. KOCH.

MICBOMETER.

APPLICATION man JUNE 27. 1911.

Patented Jan. 22, 1918.

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7 Ml llll WITNESSES Mum.

A TTOR/IIEVS WILLIAM E. RUSH, F BROOKLYN, NEW YORK.

MICBOMETEE.

matter. I

specification of Letters Patent. Patented diam, $2, jllWlE,

Application filed June 27, 1917. serial No 177,257.

To all whom itmay concern:

Be it known that 1, WILLIAM E. Kocnt, a

citizen of the United States, and a resident of the city of New York. borough of Brook lyn, in the county of Kings and State of New York, have invented a new and Improved Micrometer, of which the following is a full, clear, and exact description.

My invention relates to micrometers, and has reference more particularly to the m1- crometer scale.

An object of the invention is to provide a combination metric and English scale for micrometers so that conversion from one to the other can be made qulckly and accurately, as requlred 1n mlcrometrlc measuremerits.

Another object of the invention is. to provide a micrometer which can be used with either system of measurement.

With the above and other objects in view, I

the nature of which Will more fully appear as the description proceeds, the invention consists in the novel construction, combination and arrangement of parts as herein fully described, illustrated and claimed.

In the accompanying drawings, forming part ofthe application, similar characters of reference indicate corresponding parts the ordinary longitudinal'scale 4, which is in fractions of an inch when it is primarily designed for use with the English system. lhe thlmble or barrel 5 has also a scale 6 correspending with the'scale 4:.

To utilizesuch a micrometer in conjunction with the metric system, I provide a scale 7 on the sleeve 3, which scale is disposed along a spiral running on the barrel, the

a zero of the spiral scale coinciding with the Zero of the longitudinal or straight scale 4.

The itch of the spiral scale 7 depends on the pitch of the screw on the spindle 8, there fore the number of threads per inch of sight llne on the sleeve is equal to y where (2 equals pitch of screw, forty threads per inch, as commonly utilized in the English micrometers; 0, lead of screw in milli-.

meters equals .635001; b, .01 of a millimeter d1visions .on scale 9 of the barrel 5, said scale running alongside the scale 6 on the barrel. There are fifty of such divisions on the barrel as will be noted; therefore 5 equals .50. By substitution, the number of threads per inch of sight line will be equal to 10.80008. The spiral-line is then divided and numbered successively, only the entire units being shown on the scale, the half millimeters being indicated by short lines.

Any reading taken on either of the scales 7 or 4. by the barre orthimble5 will give a corresponding rea ing on the other scale, thereby automatically performing the converslon from one system of measurement to the other. For example, as shown in Fig. 2, the reading on the micrometer on the En lish scale is .40 of an inch; on the metric scale the reading is 10.16.

It is evident that in cases where the micrometer has a straight scale of the metric system, that is to say, the thread for the thimble is a metric thread, then the spiral a scale will carry the divisions of a scale of the English system. It may be further remarked that it is not necessary to provide two scales on the thimble, but it is to advantage, for the divisions of the metric scale may be made finer, that is, to be read to a greater fractionthan that of the English system.

ln Fig. 3 the spiral scale 7' of the metric system is of a coarser pitch. In consequence the English scale will not be in a straight line but on a spiral line l0 running in an opposite direction to the spiral 7 While I have described the principle of operation, together with the device which I now consider to be the best embodlment thereof, ll desire to have it understood that the device shown is merely illustrative and that such changes may be made as are 'wlthm the scope of the appended claims.

I claim: 1. In a micrometer, a sleeve having linear scales of the English and metric systems, one of said scales being disposed on a straight line parallel to the elements forming the sur-.

face of the sleeve and the other of said scales being disposed on a spiral about the proportional to its rotary movement, said last mentioned scale being adapted to cooperate with the scales on the sleeve.

2; In a micrometer, a sleeve having linear scales of the English and metric systems,.the

English scale being disposed on a straight line running parallel to the axis of the sleeve and the metric scale on a sfiiillztl the zeros of said scales coinciding, a t ble movable over the sleeve, longitudinally and revolubly, means for moving the thimble so that its longitudinal movement is proportional to its rotary movement, and a scale about the circumference of said thimble disposed to cooperate with the scales on the sleeve.

3. In a micrometer, a sleeve, linear scales of the English and metric systems on said sleeve,'one of said scales being disposed on a straight line parallel to the axis of the sleeve and the other on a spiral, the two scales originating from a common point, a thimble movable over the sleeve, longitudinally and revolubly, means for moving the thimble so that its longitudinal movement is proportional to .its rotary movement, the pitch of the spiral scale bearing a predetermined relation to the movement of the thimble over the sleeve, and a scale or scales about the circumference of the thimble disposed to cooperate with the scales on the sleeve.

WILLIAM F. KOCH. 

